Semiconductor integrated circuits (ICs) are formed in a plurality on a semiconductor wafer, and are then separated into individual chips for practical use. The ICs are normally subjected to an electrical test for evaluating the performance in advance of the separation into individual chips.
In this electrical test, a probe such as a probe card provided with a plurality of probes to be electrically connected to electrodes of respective device under the test, such as the above ICs, that is, an electrically connecting device is used, and the device under test are connected to a tester, as a testing means, through the electrically connecting device.
One of known probes used for the electrically connecting device is one that includes a plate-like probe body, an arm section provided in the probe body, and a probe tip section, which is provided at the tip of the arm section and is brought into contact with the electrode of a device under the test (see, for example, JP 2008-190885 A). By forming the probe body from a sturdy yet flexible metal material, when the probe tip section is pushed on the electrode of a device under the test, it is possible to cause the probe tip to slide on the electrode of the device under the test in accordance with elastic deformation of the arm section. Due to the slide of the probe tip, it is possible that the oxide film on the electrode of the device under the test will be scratched. That is, by applying an overdrive action, which causes the probe body to be elastically deformed, and thus, it becomes possible for the probe to come into contact and to remove the oxide film on the electrode by means of the probe tip and to obtain a reliable electrical contact therebetween.
Probes like this are formed in the following manner. First, a silicon wafer is prepared as a baseboard, and a plane pattern of the entire probe area is replicated on the baseboard using a photoresist through a photolithographic technique. Next, a desired material is deposited on a recess of the baseboard, which has been replicated using the photoresist. Then, the probes can be manufactured by being removed from the baseboard after having been formed thereon as disclosed in, for example, JP 2008-164575 A and JP 2008-191027 A.
In order to remove the formed probes from the baseboard, an etching technique is utilized. On the baseboard, there is formed, for example, a sacrificial layer composed of a metal material such as, for example, copper or the like, different from the material of the probes, and the probe material is deposited on the sacrificial layer. By removing the sacrificial layer by means of, for example, wet etching using an etching liquid, the formed probes can be removed from the baseboard by peeling.
However, since plural probes are collectively formed on the baseboard, if an etching process is performed until the sacrificial layer under the probes is completely removed, the plural minute probes may float in the etching liquid, which causes difficulty in the handling thereof.
It is therefore desirable to complete the etching process for forming the probes at the state in which the sacrificial layer remains at an appropriate minimum area between the probes and the baseboard as support portions, which serves for removing the probes easily. In that case, the probes remaining on the baseboard can be respectively removed by being peeled off using a tool.
In that case, however, if the time spent for the etching process described above is short, there remains a large quantity of the sacrificial layer between the probes and the baseboard as support portions. A strong force is required to peel off the probes adhered on the baseboard due to the remaining large quantity of sacrificial layer (support portions). In addition, such a process may deform the probes.
For this reason, there is a known method in which, when forming probes on a baseboard, the recess on the baseboard, replicated using a photoresist, is configured in a predetermined shape, and the probes and fixing tabs connected thereto for fixing the probes are integrally formed by depositing the probe material on the recesses, as disclosed in JP 2008-191027 A.
FIGS. 1A and 1B are drawings for explaining a known method for manufacturing a probe; FIG. 1A is a plan view schematically showing a probe and a fixing tab, and FIG. 1B is a cross-sectional view schematically showing the probe and the fixing tab on a baseboard.
In FIGS. 1A and 1B, the shape of a probe 1001 is schematically illustrated for the sake of convenience.
As shown in FIG. 1A, the probe 1001 and a fixing tab 1002 connected to the probe 1001 via a connecting portion 1004 are formed on a baseboard (not shown in FIG. 1A).
In this known method for manufacturing the probe 1001, the sacrificial layer between the probe 1001 and the baseboard 1005 is fully removed without any of the sacrificial layer remaining by means of the etching process described above, and at the same time only one sacrificial layer portion having predetermined pattern and area is left between the baseboard 1005 and the fixing tab 1002 as a support portion 1003, as shown in FIG. 1B. The fixing tab 1002 has a plane pattern that is suitable to leave the sacrificial layer portion under the fixing tab 1002 when the sacrificial layer under the probe 1001 is removed through the etching process. Consequently, in the known method for manufacturing the probe 1001, the etching process is performed such that, with respect to the respective probes 1001 on the baseboard 1005, only one support portion 1003 is left between the baseboard 1005 and the fixing tab 1002 connected to each of the probes 1001.
After that, in the known method for manufacturing the probes 1001, each of the probes 1001 is separated from the fixing tab 1002 supported by the support portion 1003 on the baseboard 1005. The separation of the probe 1001 is implemented by decoupling the connecting portion 1004 at a predetermined position as schematically illustrated with a dotted line in FIG. 1A. As a result, the probe 1001 can be removed from the baseboard 1005 without undergoing damage during the peeling process described above.
However, in the known method for manufacturing a probe, it occasionally happens that stresses arising in a probe and/or fixing tab due to a heat treatment and the like performed during the process of manufacturing probes concentrate onto the fixing tab causing the fixing tab to become warped. As a result, it has occurred that the probe formed on a baseboard has peeled off and dropped from the baseboard in a state of still being connected with the fixing tab, which has caused the yield of manufacturing probes to be lowered.
A method for manufacturing a probe is therefore desired that enables reduction in the occurrence of the dropping of the probes, which have been formed on a baseboard, from the baseboard during the manufacturing process.
The present invention has been performed in view of the problem of dropping of probes from a baseboard, which happens in the known method for manufacturing a probe.
An object of the present invention is therefore to provide a method for manufacturing a probe that reduces the occurrence of the dropping of probes from a baseboard.
Other challenges and advantages of the present invention are apparent from the following description.